1. Field of the Invention
The present invention relates to an apparatus for use in monitoring the position of a patient relative to a support surface such as a bed.
2. Description of the Prior Art
There is a need for effective signalling of a caregiver when a patient moves from one position to another in a bed. For example, such a need exists when a patient, who is likely to suffer injury and sometimes death by leaving his bed without assistance, falls or gets out of bed.
Various patient monitors are known in the prior art. For example, U.S. Pat. No. 4,020,482 to Feldl relates to a patient monitor including an elongated air inflated flexible bag placed below a mattress and connected to a pressure actuated electrical switch at a remote station. The switch is a normally closed low pressure switch which remains open as long as a patient's weight is on the mattress and closes when the patient's weight is removed. In essence, removal of the weight lowers the pressure in the bag which closes the switch.
U.S. Pat. No. 3,533,095 to Collins is of interest in that an air mattress is provided upon which an animal is placed in a first position. For example, a mare is placed upon the mattress in a standing position. When the mare lies down the displacement of her weight causes air from the mattress to expand into a connection to a normally open pressure switch, thereby closing the switch and activating an alarm.
U.S. Pat. No. 3,781,843 to Harrison et al. is of interest in that pressurized fluid is contained in members having a fluid filled passageway which can be attached to the side rails, etc. of a bed. When someone gets out of the bed he typically will grasp such rails and activate an alarm.
U.. Pat. No. 4 175 263 to Triplett et al. is of interest in that it relates to a plurality of pressure sensors for sensing when a patient is in the normal position in a bed and when a patient begins to leave the bed. A pressure sensitive switch and an alarm are also provided.
U.S. Pat. No. 4,633,237 to Tucknott et al. describes a patient bed alarm system which includes multiple sensors which define interstices of a matrix woven into a mat for placement on a bed. The system is used in combination with a microprocessor control. The presence of the patient's body at various combinations of sensors is used to identify the location of the patient and an alarm is provided if the combination of sensors indicate impending vacation of the bed.
U.S. Pat. No. 3,439,358 to Salmons describes detecting movement of a human upon a bed by generating electrical signals which are received by receiving means such as a receiving antenna. Signals are thereby provided for recording such movement.
U.S. Pat. No. 4,907,845 to Wood describes a bed patient monitoring system for determining whether there is a likelihood that the patient is trying to leave the bed. To this end a sensor which utilizes ribbon switches is placed under the mattress next to the bed frame.
U.S. Pat. No. 4,228,426 to Roberts, U.S. Pat. No. 4,242,672 to Gault, U.S. Pat. No. 4,638,307 to Swartout and U.S. Pat. No. 4,700,180 to Vance relate to the use of electrical switches which are directly actuated by contacts which close under the weight of a patient and open when such weight is removed to activate an alarm which indicates the presence or absence of a patient relative to a bed.
United States patents of general interest regarding the monitoring of movement include U.S. Pat. Nos. 4,337,726 and 4,899,133 to Czekajewski et al and Bartlett, respectively.
It is an object of the present invention to provide a position monitor, for use with a patient in a bed, which is relatively simple in construction.
It is another object of the present invention to provide a position monitor for use with a patient in a bed to alert the caregiver when the patient has moved from an original location after placement upon a support surface.
It is also an object of the present invention to provide such a position monitor which will alert the caregiver when the patient has moved off center towards an edge of a support surface.
Another object of the present invention is to provide such a position monitor which will alert the caregiver when the patient has actually moved to an edge of a support surface.
A further object of the present invention is to provide such a position monitor for use with a patient in a bed which will allow the caregiver to determine that a patient is about to fall or get out of the bed before the eventuality occurs.
Yet another object of the present invention is to provide such a position monitor which will alert the caregiver that the patient is in the middle of the bed.
It is also an object of the present invention to provide such a position monitor which will alert the caregiver when a patient is lifting his body away from the middle of a bed in a possible attempt to leave the bed.